title: Drinking water turbidity and emergency department visits for gastrointestinal illness in Atlanta, 1993-2004.
abstract: The extent to which drinking water turbidity measurements indicate the risk of gastrointestinal illness is not well understood. Despite major advances in drinking water treatment and delivery, infectious disease can still be transmitted through drinking water in the United States, and it is important to have reliable indicators of microbial water quality to inform public health decisions. The objective of our study was to assess the relationship between gastrointestinal illness, quantified through emergency department visits, and drinking water quality, quantified as raw water and filtered water turbidity measured at the treatment plant. We examined the relationship between turbidity levels of raw and filtered surface water measured at eight major drinking water treatment plants in the metropolitan area of Atlanta, Georgia, and over 240,000 emergency department visits for gastrointestinal illness during 1993-2004 among the population served by these plants. We fit Poisson time-series statistical regression models that included turbidity in a 21-day distributed lag and that controlled for meteorological factors and long-term time trends. For filtered water turbidity, the results were consistent with no association with emergency department visits for gastrointestinal illness. We observed a modest association between raw water turbidity and emergency department visits for gastrointestinal illness. Our results suggest that source water quality may contribute modestly to endemic gastrointestinal illness in the study area. The association between turbidity and emergency department visits for gastrointestinal illness was only observed when raw water turbidity was considered; filtered water turbidity may not serve as a reliable indicator of modest pathogen risk at all treatment plants.
authors.affiliation: Rollins School of Public Health, Emory University, Atlanta, Georgia, USA. sceaser@sph.emory.edu
authors.forename: Sarah C
authors.initials: SC
authors.lastname: Tinker
authors.forename: Christine L
authors.initials: CL
authors.lastname: Moe
authors.forename: Mitchel
authors.initials: M
authors.lastname: Klein
authors.forename: W Dana
authors.initials: WD
authors.lastname: Flanders
authors.forename: Jim
authors.initials: J
authors.lastname: Uber
authors.forename: Appiah
authors.initials: A
authors.lastname: Amirtharajah
authors.forename: Philip
authors.initials: P
authors.lastname: Singer
authors.forename: Paige E
authors.initials: PE
authors.lastname: Tolbert
mesh_terms: D002947:Cities / Q000453:epidemiology; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005374:Filtration / Q000706:statistics & numerical data; D005767:Gastrointestinal Diseases / Q000453:epidemiology* / Q000382:microbiology / Q000469:parasitology; D005845:Georgia / Q000453:epidemiology; D006801:Humans; D009391:Nephelometry and Turbidimetry; D011786:Quality Control; D018570:Risk Assessment; D013997:Time Factors; D014504:Urban Health / Q000706:statistics & numerical data; D014876:Water Pollution / Q000009:adverse effects / Q000032:analysis* / Q000706:statistics & numerical data; D018508:Water Purification / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data; D014881:Water Supply / Q000032:analysis* / Q000592:standards / Q000706:statistics & numerical data*